1. Technical Field
The invention relates to loudspeakers and, more particularly, to acoustical horns or waveguides for use in loudspeakers.
2. Related Art
Typically, a loudspeaker includes a driving unit that is coupled to a horn. The large end of the horn, called the “mouth,” typically has an area large enough to radiate sound efficiently at a desired low frequency. The small end of the horn, called the “throat,” has an area selected to match the acoustic impedance and exit diameter of the driving unit and to reduce distortion of the acoustic signal.
The loudspeaker horn guides the acoustic signal or acoustic energy into particular directions or regions. The loudspeaker horn surfaces that constrain and control the radiation of acoustic energy are commonly referred to as an acoustic waveguide. The surfaces of an acoustic waveguide in a loudspeaker typically produce a coverage pattern of a specified total coverage angle that may differ horizontally and vertically. The coverage angle is a total angle in any plane of observation (although typically horizontal and vertical orthogonal planes are used). The coverage angle is evaluated as a function of frequency and is defined to be the angle at which the intensity of sound, or sound pressure level (SPL), is half of the SPL on the axis (the reference axial direction is usually normal to the throat of the driver).